Electrostatic relay



April 15, 1947. M v,oh BQSTWlQK 2,419,111

ELECTROSTATIG RELAAY Filed 001'.. 22 1942 3 Sheets-Sheet l Fig; Z.

wnNEssEs: xNvENToR April 15, 1947. M, A BOSTWlCK n 2,419,111

ELECTROSTATIG RELAY Filed Oct. 22, 1942 `C5 Sheets-Sheet 2 B /C ynNr-:ssr-:s: C/ :E/C/ INVENTOR /7 fan/asf fr.

@M2M www ATTORNEY pri 15, 1947. v M. A. BosTWlcK 2,419,111

ELECTROSTATIC RELAY Filed Ooi. 22, 1942 3 Sheets-Sheet 5 wlNEssE's: INVENTOR ATTOR N EY Patented Apr. 15, 1947 ELECTRO STATIC RELAY Myron A. Bostwick, Budd Lake, N. J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 22, 1942, Serial No. 463,015

(Cl. 20G-87) 2 Claims.

This application relates to electrical relays and it has particular relation to electrical relays of the electrostatic type.

Electrostatic relays are well known in the art. As a specific example, reference may be made to the Bostwick et al. Patent 2,020,931, wherein an electrostatic relay is disclosed for controlling the tripping of a network protector in a network distribution system. However, because of the inability of the prior art to provide an electrostatic relay of simple and sturdy construction suitable for high voltage installations, the application of the electrostatic relay has been unduly restricted.

In accordance with the invention, a pair of relatively movable members between which an electrostatic eld is produced are positioned in a sealed housing. This housing contains a din electric fluid which preferably is a liquid. This liquid serves not only as a dielectric, but it also serves to insulate the members and to damp the relative movement thereof. Furthermore, the dielectric liquid renders the electrostatic relay substantially shock proof.

Although the dielectric liquid affords a substantial degree of insulation, the invention includes an insulating coating for the relatively movable members. This insulating coating guards against dielectric breakdowns caused by dust and air bubbles in the dielectric liquid.

The invention further contemplates the provision of circuit controlling mechanism positioned externally of the housing containing the relatively movable members` An operating force is transmitted from the relatively movable members to the circuit controlling mechanism by a magnetic coupling. The provision of such a coupling permits the utilization of a completely sealed housing for containing the dielectric liquid.

It is, therefore, an object of the invention to provide an-improved electrostatic relay.

It is a further object of the invention to pro- I vide an electrostatic relay having relatively movable electroconductive plates immersed in a dielectric liquid contained in a sealed housing.

It is another object of the invention to provide an electrostatic relay having electroconductive plates immersed in a dielectric liquid and having an insulating coating on at least certain of the electroconductive plates.

It is a still further object of the invention to provide an electrostatic relay having relatively movable electroconductive plates and having circuit controlling mechanism coupled to the plates by means of a magnetic coupling. f

Other objects of the invention will be apparent from the following description, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a view in front elevation with parts in section of an electrostatic relay embodying the invention;

Fig. 2 is a view in top `plan with parts removed of the electrostatic relay illustrated in Fig. 1;

Fig. 3 is a view in side elevation with parts in section of the electrostatic relay illustrated in Fig. 1:

Fig. 4 is a detail View of a sealing cap suitable for the relay of Fig. 2;

Figs. 5, 6 and 7 are schematic views showing electrical coupling systems suitable for the electrostatic relay of Fig. 1;

Figs. 8, 9 and 10 are detail views in perspective with parts in section showing modilied means for associating circuit completing mechanism with an electrostatic relay designed in accordance with the invention.

Referring to the drawings, Fig. 1 shows an electrostatic relay provided with a housing l. This housing includes a cup-shaped base receptacle 3 having a cover 5 associated therewith. As shown more particularly in Figs. 2 and 3, the cover 5 maybe attached to the base receptacle 3 by any suitable means, such as machine screws 1. It will be observed that the cover 5 is provided with a peripheral flange 9 which substantially increases the rigidity of the cover. The cover and base receptacle may be formed of any suitable material, such as aluminum or a diecast alloy. To assure agood seal between the cover and the base receptacle, a gasket Il may be placed therebetween. By inspection of Figs. 1 and 2, it will lbe observed that ears I3 and |74 are associated'with the base receptacle 3. These ears facilitate the mounting of the electrostatic relayr on any desired support.

The operating force for the electrostatic relay is provided by a iixed assembly I5 which is attached integrally or otherwise to the cover 5` and a movable assembly I1 which is mounted for rotation relative to the cover 5. The rotatable assembly l1 includes one or more electroconductive plates. Although the number of electrical conductive plates may vary appreciably, two plates I9 and 2| are illustrated in the speciiic embodiments of Figs. 1, 2, and 3. These plates may be stamped from a single sheet of suitable material, such as aluminum. A connecting portion 23may Y spacing these plates.

be left between the two electroconductive plates.

To support the electroconductive plates I9 and 2l for rotation, a suitable shaft assembly is provided. Preferably, the shaft assembly insulates the electroconductive plates i9 and 2l from the remainder of the electrostatic relay. In the specic embodiment herein illustrated, a pair of threaded rods of insulating material 25 are pro vided. These rods may be formed of any suitable material such as phenolic resin. Each of the rods is provided at its ends with a pair of caps 2l and 29 which are in threaded engagement therewith. The caps 2S are provided with flanges 3l to which the movable assembly is attached in any suitable manner as by rivets 33 and bolts 35. The caps 2l are provided with shafts 31 which are received in bearings 39 and il carried by the cover 5.

The fixed assembly I is divided into two electroconductive plates 43 and 45, having surfaces respectively adjacent surfaces of the electroconductive plates I8 and 2I of the rotatableV assembly. By inspection of Fig. l, it will be observed that when an electrostatic iield is established between the xed assembly I5 and the rotatable as- Yare bridged by an integral connecting member 47 which has a threaded opening for the reception of the bearing screw 39. A lock nut 45 may be provided for retaining the bearing screw 39 in any position of adjustment thereof.

The remaining bearing screw 4I maybe received in a threaded opening in the cover 5. In thismanner, the rotatable assembly I'I is mounted for rotation with respect to the iixed assembly I5 and is removable therewith as a unit from the base receptacle 3.

Since high voltages are to be applied between the iixed and movable electroconductive plates, it isdesirable that stops be provided for accurately For this purpose each of the xed electroconductive plates is provided with arecess 5I (see Fig. 3) within which a stop member 53 is positioned. This stop member may be formed of any suitable insulating material such "as a phenolic resin. To permit adjustment of the stop member 53, it is mounted in any suitable manner on a machine screw 55 which is received in a threaded opening 56 in the associated "fixed electroconductive plate.

A lock nut 51 may be provided for locking the machine screw 55 in any position'to which it is adjusted. By inspection of Fig. 3, it will be observed that the stops Y53 may be accurately positioned to determine the minimum space between the fixed electroconduc- Ative plates 3 and 45 and the respective movable 'hydrocarbon petroleum product, such as kerosene,

has been employed with satisfactory results. As previously pointed out, the liquid dielectric lserves notY only as a dielectric but as a damping medium Vfor the rotatable assembly I'I and as an insulating means. f By suitable selection'of the dielectric liquid, the time of response of the electrostatic Yrelay may be varied substantially. Because ofthe Ypresence of the dielectric liquid, the electrostatic relay is subst'antiallyimmune to vibration and shock.

in the magnetic fields pr nent magnets 'll and '13.

Vcured to the inc When the housing I contains a fluid dielectric, it is desirable that all electrical and mechanical connections to elements positioned within the housing be provided with satisfactory seals for preventing the escape or contamination of the dielectric iiuid. To this end, the contacts for the electrostatic relay may be actuated from the rotatable assembly Il through a magnetic coupling.

Referring to Fig. 1, it will be observed that a bar 63 is connected by any suitable means such as machine screws 65 to the cap 2I for rotation therewith. At its ends the bar 53 carries a pair of posts El which project through openings B9 in the cover 5. rIhe bar 63 and posts SI may be formed or aluminum. Each of the posts 6l has attached thereto a permanent magnet 1I or I3 by any suitable means such as a machine screw l5. These permanent magnets preferably are 0i high coercive material such as permanent magnet steel containing cobalt.

For housing the permanent inagnets'll vand T3, a pair of caps i? are provide-:l each of which comprise a cylindrical cup Il of non-magnetic material, such as brass. This brass cup ave male threads EI for threaded recepieinale threads S3 provided in the cover 5. If des ed, each of the cups i9 may be provided with a cylindrical cover 35 of an'insulatingy n'onmagna lc aterial such as a phenolic resin. The cover c.. ay be secured in position in any suitable manner. in the illustrated embodiment (Fig. 1i) cover is secured between a ilange 18a med ou the cup if) and a resilient split ring .vii-o 'v is positioned in an annular slot 'IBC formed in the cup 1S. By inspection oi Figs. l and 2, it will be observed that rotation of the rotatable assembly l'I operated to move each of the permanent magnets `II and "f3 within its cup E. Each cup 'it may be provided with an elongated rib '55a which may be engaged to facilitate rotation and removal ci the cup.

For cooperation with Athe permanent magnet-s "II and a contact asse'cibly is provided having iositioned respectively .iuced by' the perma- This contact assembly may be secured to an insulating block SI which magnetic arms 8'! and 88 is attached to the cover 5 in any suitable manner as by machine screws 93. rEhe magnetic arms 5l and 5S may be attached in any suitable manner to the ends of a resilient stri of any suitable material, such as bronze. This strip is seoting block 5I by means of vhich are received in threaded machine screws bushings 59 afhed to the insulating block 9|.

For controlling the position and effective resiliency ci the strip 55, a plurality of adjusting screws IGI are positioned in a bar ISE which also issecured to the insulating block QI Aby the machine screws 5l. Suitable spacers IIl5and IGT are provided for spacing the strip S5 and the bar IU3.

The magnetic arms Sl and 89 carry respectively, movable contacts ISE and lIil which coopcrate with fixed contacts vI II and II3. The xed contacts il! and H3 may be carried by strips i l ci' suitable material such as brass. These strips are secured to the insulating block SI by means of machine screws I il. If desired, adjust- 'ig screws H9 and supports therefor may be provided for adjusting the positions of the fixed contacts Ila' and Il3. The resiliency of the strips II5 permits a sufficient range of adjust- `nient for the fixed contacts.

VIt will be observed that movements of the permanent magnets 1| and 13 vary the distance between each permanent magnet and its associated magnetic arm 81 or 89. When the permanent magnet 1| or 13 is at its maximum distance from its associated magnetic arm 81 or 89, the magnetic force therebetween is insufcient to'overcome the resiliency of the strip 95 and the associated contacts remain open. As each of the permanent magnets approaches its associated magnetic arm, a point is reached at which the magnetic force developed therebetween becomes large enough to overcome the resiliency of the strip 95, whereupon the associated movable contact moves into engagement with the associated i'lxed Contact. Consequently, contact operation is provided without destroying the seal provided by the housing for the iluid dielectric contained therein.

Since the magnetic force developed between each of the permanent magnets 1| and 13 and its associated magnetic arm increases as each magnetic arm and associated permanent magnet approach each other, a substantial force is required to separate each permanent magnet and its associated magnetic arm following a closing operation of the associated contacts. To reduce the operating force required for this purpose and to provide adequate control for the electrostatic relay, a plurality of control springs |2|, |23 and |25 are provided. These springs may be each secured at one end to supports |21, formed on the fixed assembly |5, b-y means or machine screws |29. These springs extend substantially parallel to the posts 61 with their free ends projecting through the openings 69 formed in the cover 5. The posts 61 carry machine screws |3| which form adjustable abutments for engaging the associated springs |2|, |23 and |25. By inspection of Fig. l, it will be observed that the machine screws |3| may be adjusted following removal of the caps 11.

When a voltage is applied between the xed and rotatable assemblies l5 and l1, the electrostatic field therebetween produces a force urging therotatable assembly |1 counterclockwise as viewed in Fig. 2. Counterclockwise rotation of the rotatable assembly |1 carries the permanent magnet 1| towards its associated magnetic arm 81. Consequently, the permanent magnet 1| may be termed an overvoltage magnet and the contacts |99 and may be termed overvoltage contacts. This rotation of the rotatable assembly l1 is opposed by the control spring |25. By proper adjustment of the machine screw |3| associated with the control spring |25, the voltage at which the permanent magnets remain substantially equidistant from their magnetic arms 81 and 89 may be adjusted within suitable limits.

As the overvoltage permanent magnet 1| approaches its associated magnetic arm 81, a point is reached at which the control spring |23 is engaged by its associated machine screw |3|. This control spring |23 introduces a force acting on the rotatable assembly |1 to oppose the increased magnetic force of attraction resulting from the close approach of the permanent magnet 1| to the associated magnetic arm 81. Since the control spring |23 tends to separate the overvoltage permanent magnet 1| from its associated magnetic arm 81, the control spring |23 may be vreferred to as an overvoltage kick-out spring.

. When the voltage applied between the xed and rotatable assemblies |5 and I1 decreases, the

.control spring |25 urges the rotatable assembly in a clockwise direction, as 'viewed in Fig, 2. Such movement of the rotatable assembly carries the permanent-magnet 13 towards its associated magnetic arm 89. At some pointin this approach, the magnetic force between the permanent magnet 13 and its associated magnetic arm 89 becomes suilicient to overcome the resiliency of the strip and the contacts ||0 and ||3 thereupon close. For this reason, the permanent magnet 13 may be referred to as an undervoltage permanent magnet and the contacts ||0 and I3 may be referred to as undervoltage contacts.

The clockwise rotation of the rotatable assembly also carries one of the machine screws |3| into engagement with the control spring |2I. rl`his control spring |2| produces a force opposing the force of attraction between the undervoltage magnet 13 and the associated magnetic arm 89. For this reason, the control spring |2| may be termed an undervoltage kick-out spring.

Although the contacts |09, ||9 and ||3 may be employed directly for a control operation, a contactor |33 may be associated therewith as indicated in Fig. 2. This contactor may be of a well known solenoid-operated type. As shown in Fig. 2, conductors may extend between the contacts |89, ||9 and ||3, the contactor |33 and terminalsy |35, |33 andy |31. As a specific example of suitable contact connections, the xed contacts and ||3 may be connected in parallel through conductors |39 and |40 to one of the terminals |35. The movable contacts |09 and H0 may be connected in parallel through a conductor |43 to the winding of the contactor The remaining terminal of the winding of the contactor |33 may beconnected through a conductor |45 to the terminal |36. The contacts of the contactor |33 may be connected through conductors |41 and |49 to the terminals |35 and |31. These connections will be discussed further with reference to Fig. 5.

The terminals |35, |35 and |31 may be of any suitable form. As illustrated more particularly in Fig. 3, each of these terminals may include an insulating sleeve |5| of any suitable material such as a phenolic resin. This sleeve extends through the cover 5 and is provided withan enlarged head |53 for restricting axial movement thereof. A collar |55 is attached to the insulating sleeve |5| in any suitable manner on the side of the cover '5 opposite the head |53 to prevent `axial movement of the insulating sleeve. A conductor |51 extends through the sleeve |5| and terminates at one end in a Contact blade |59. This contact blade |59 is designed for reception in a contact jaw |6|. The opposite end of the conductor |5| may be attached to a terminal lug |63. The contact jaws ||5| may be carried by suitable insulating structures |64 which are mounted on brackets |35. These brackets |65 are illustrated as attached to a support |61 by means of suitable bolts |69.

The support |61 also includes flanges |1| to which the electrostatic relay may be attached. Referring to Fig. 1, it will be observed that the flanges |1| support the ears 3 and I4. Each of these ears is provided with a jack screw |13 having a collar |15 attached thereto in any suitable manner to restrict axial movement of the screw with respect to the associated ears. These jack screws are received in threaded openings |11 provided in the flanges |1|. By inspection of Fig. l, it will be observed that rotation of the jack screws |13 positively` moves the electrostatic reveloped between `the movable electroconductive plates I9 and 2l and the xed plate 43 and 45 decreases. In response to this decrease, the control spring I25 urges the'undervoltage magnet 13 towards its associated magnetic arm 89. At a predetermined point, the permanent magnet 'I3 attracts the magnetic arm 89 suiiiciently to close the contacts IIB and I I3. As shown in Fig. 5, closure of the contacts I II! and H3 completes an energizing circuit for the winding of the contactor |33. The contactor thereupon picks up to close its contacts and energize the trip coil 2 I 3.

Should the voltage across the electrostatic relay increase as in response to a phase-to-ground fault occurring on one of the conductors C or B, the electrostatic force developed between the fixed and movable plates increases to an extent` suicient to close the contacts |09 and III. In response to such closure, the energizing winding of thefcontactor I33 is energized to complete a circuit for the tripping coil 2 I 3.

A still further coupling system for the electrostatic relay is illustrated in Fig. 6. With a system as illustrated in Fig. 6, a phase-to-ground fault on the phase conductor A results in an ap plication to the electrostatic relay of a voltage represented by the following expression:

Although a preferred magnetic coupling is illustrated in Figs. 1, 2 and 3, for actuating the relay contacts several modiiied constructions are illustrated in Figs. 8, 9 and 10, In Fig. 8, the rotatable assembly II has attached thereto a magnetic bar 2I5 having north and south poles represented by the reference characters N and S. The rotatable assembly I1 is enclosed in a housing IA similar to that of Figs. 1, 2 and 3. This housing IA is provided with a cover 5A of nonmagnetic material corresponding to the cover 5 of Figs. 1, 2 and 3. External to the housing a second permanent magnet 2I'I is mounted for rotation on a shaft 2I9. The permanent magnet 2I1 has north and south poles which again are represented by the reference characters N and S. Since the permanent magnets 2|5 and 211 are mounted with the smallest spacing possible between the poles thereof, movement by one of the permanent magnets is accompanied by movement of the remaining permanent magnet. The shaft 2I9 may carry a movable contact 22| for engaging iixed contacts 223 and 225, The iixed contacts may be mounted on suitable insulating supports 221. The construction of Fig. 8 is somewhat less desirable for the reason that the relatively loose coupling between the permanent magnets and the high inertia of the moving parts makes the assembly somewhat subject to operation by mechanical shock.

Alternatively, a shaft 230 which supports the rotatable assembly I'I (Fig. 9) may be extended through the cover 5B which corresponds .to the cover 5 of Figs. l, 2 and 3 through an oil seal bearing 23I. It will be understood that the rotatable assembly I1 is positioned within a housing IB which otherwise corresponds to the houslng 2 of Fig. 1. Although such a construction may be operated successfully, it is objectionable for the reason that some oil and air leakage takes place through the bearing 23|. It should be observed that any increase in bearing friction resulting from an attempt to decrease the leakage through the bearing is objectionable for the reason that such an increase in friction objectionably loads the rotatable assembly Il.

In the modification illustrated in Fig. 10, the rotatable assembly I1 also is enclosed in a housing IC corresponding to the housing I of Figs. 1, 2 and 3. A switch of suitable design, such as a mercury switch 223, is mounted in the same housing. `As a specific example, the switch may be mounted for rotation on a shaft 2 35. Rotation of the shaft is effected by an arm 231 attachedto the' rotatable assembly II. This arm passes through an eye 239 carried by the shaft 235. Connections from the switch may be carried by iiexible conductors through the cover 5C which corresponds to the Cover 5 of Figure 1, 2 and 3. A suitable insulating material, such as rubber or a phenolic resin 24|, may be employed for sealing the opening through which the conductors 243 from the switch pass. For many applications such a construction is less desirable than that i1- lustrated in Figs. 1, 2 and 3 for the reason that substantial energy is required to actuate the switch 233.

Although the invention has been described with reference to certain specific embodiments thereof, numeraus modifications thereof are possible. Therefore, the invention is to be restricted only by the appended claims as interpreted in view of the prior art.

I claim as my invention:

1. In a relay device, a pair of spaced electroconductive plates, means mounting said electroconductive plates for movement relative to each other, means for establishing an electrical field between said electroconductive plates, said electrical iield operating to urge one of said electroconductive plates relative to the other of said electroconductive plates in a predetermined direction, a completely sealed housing for said electroconductive plates, and circuit controlling means responsive to the relative movement of said members, Isaid circuit controlling means comprising a pair of permanent magnets, means mounting said permanent magnets for movement Within said housing in accordance with relative movement of said electroconductive plates, said housing having a non-magnetic wall positioned adjacent each of said permanent magnets for permitting passage of magnetic iiux from each of said permanent magnets therethrough, and control means positioned exteriorly of said housing, said control means having a separate magnetic operating member positioned in the path of magnetic flux from each of said permanent magnets for actuating said control means in accordance with movement of each of said permanent magnets, each of said magnetic operating members being positioned for operative attraction by its associated permanent magnet in response to relative movement of said electroconductive plates in a separate direction.

2. In a relay device, a pair of spaced electroconductive plates, means mounting said electroconductive plates for movement relative to each other, means for establishing an electrical field between said electroconductive plates, said electrical field operating to urge one of said electroconductive plates relative to the other of Said electroconductive plates in a predetermined directiomaninsulating coa-tingen one `ofsaid elec-`v troconductiveplates, means biasing saidelectrot-V conductive plates in opposition `to the force developediby said electrical field, a completely sealed housingfor said electloconductive plates, anin.-V sulating liquid in said housing within which 'said electroconductive plates areimmersed, said insulating liquid operating as a fluid dielectric body between said electroconductive plates, and circuit controlling means responsive to the relative movement of said members, said circuit controlling means comprising a pair of permanent magnets, meansl mounting said permanent magnets for movement Within said housing in accordance with relative movement of said electroconductive plates; said housing having a non-magnetic Wall positioned adjacent each of saidpermanent magnets for permitting passage Aof magnetic IiuX from each. of said permanent magnets therethrough,

and control means positioned exteriorly of said 20 nent magnets. each of said `magnetic operating members being positioned for operative attraction by its associated permanent magnet. in response to relative movement of said electroconductive plates in a separate direction, and resilient means opposing attraction of each of said magnetic operatingk members by its associated permanent' magnet.

MYRON A. BOSTWICK.

REFERENCES CITED Thefollowing references are of record -in the le of this patent:

UNITED STATES PATENTS` Number Name Date 1,408,738. Hill Mar. 7, 1922 1,061,919 Miller May 13,1913 1,403,701 McCullough Jan.` 17,- 1922 1,605,911 Banneitz Nov. 9, 1926y 2,028,893 Bondurant' Jan. 28,-.1936

FOREIGN PATEN'I'SI Number. Country Date 383,595 British Nov.- 17, 1932 

